February 2018

Arctic ice melt could pause in coming decades

First the ice extent had been 50% less during the Holocene Climatic Optimum than it was in September 2007, now we have models saying the ice could expand during some decades just as easily as contract, according to this NSF press release (hat-tip to Noel):

Researchers find unexpected results in study of ice cover in the Arctic

Despite the rapid retreat of Arctic sea ice in recent years, the ice may temporarily stabilize or somewhat expand at times over the next few decades, new research indicates.

Results of a study by scientists at the National Center for Atmospheric Research (NCAR) appear this week in the journal Geophysical Research Letters (GRL), published by the American Geophysical Union.

The National Science Foundation (NSF), NCAR's sponsor, funded the work.

"As we learn more about climate variability, new and unexpected research results are coming to light," says Sarah Ruth, program director in the Division of Atmospheric and Geospace Sciences, which funds NCAR for NSF. "What's needed now are longer-term observations to better understand the effect of climate change on Arctic sea ice."

The computer modeling study reinforces previous findings by other researchers that the level of Arctic sea ice loss observed in recent decades cannot be explained by natural causes alone, and that the ice will eventually melt away during summer if the climate continues to warm.

But in an unexpected new result, the NCAR research team found that Arctic ice under current climate conditions is as likely to expand as it is to contract for periods of up to about a decade.

"One of the results that surprised us all was the number of computer simulations that indicated a temporary halt to the loss of the ice," says NCAR scientist Jennifer Kay, the lead researcher.

"The computer simulations suggest that we could see a 10-year period of stable ice or even a slight increase in the extent of the ice.

"Even though the observed ice loss has accelerated over the last decade, the fate of sea ice over the next decade depends not only on human activity but also on climate variability that cannot be predicted."

Kay explains that variations in atmospheric conditions such as wind patterns could, for example, temporarily halt the sea ice loss. Still, the ultimate fate of the ice in a warming world is clear, she says.

"When you start looking at longer-term trends, 50 or 60 years, there's no escaping the loss of ice in the summer."

Kay and her colleagues also ran computer simulations to answer a fundamental question: why did Arctic sea ice melt far more rapidly in the late 20th century than projected by computer models?

By analyzing multiple realizations of the 20th century from a single climate model, they attribute approximately half the observed decline to human emissions of greenhouse gases, and the other half to climate variability.

These findings point to climate change and variability working together equally to accelerate the observed sea ice loss during the late 20th century.

Since accurate satellite measurements became available in 1979, the extent of summertime Arctic sea ice has shrunk by about one third.

The ice returns each winter, but the extent shrank to a record low in September 2007 and is again extremely low this year, already setting a monthly record low for July.

Scientists warned just a few years ago that the Arctic could lose its summertime ice cover by the end of the century.

Some research has indicated that Arctic summers could be largely ice-free within the next several decades.

To simulate what is happening with the ice, the NCAR team used a newly updated version of one of the world's most powerful computer climate models.

The software, known as the Community Climate System Model, was developed at NCAR in collaboration with scientists at multiple organizations and with funding by NSF and the Department of Energy.

The research team first evaluated whether the model was a credible tool for the study.

By comparing the computer results with Arctic observations, they verified that, though the model has certain biases, it can capture observed late 20th century sea ice trends and the observed thickness and seasonal variations in the extent of the ice.

Kay and her colleagues then conducted a series of future simulations that looked at how Arctic sea ice was affected both by natural conditions and by the increased level of greenhouse gases in the atmosphere.

The computer studies indicated that the year-to-year and decade-to-decade trends in the extent of sea ice are likely to fluctuate increasingly as temperatures warm and the ice thins.

"Over periods up to a decade, both positive and negative trends become more pronounced in a warming world," says NCAR scientist Marika Holland, a co-author of the GRL paper.

The simulations also indicated that Arctic sea ice is equally likely to expand or contract over short time periods under the climate conditions of the late 20th and early 21st century.

Although the Community Climate System Model simulations provide new insights, the paper cautions that more modeling studies and longer-term observations are needed to better understand the impacts of climate change and weather variability on Arctic ice.

The authors note that it is also difficult to disentangle the variability of weather systems and sea ice patterns from the ongoing impacts of human emissions of greenhouse gases.

"The changing Arctic climate is complicating matters," Kay says. "We can't measure natural variability now because, when temperatures warm and the ice thins, the ice variability changes and is not entirely natural."

Interesting, but unlikely. Since the big drop off in 2007, we have had some recovery, but nothing like extent and volume previous to 2007.

With the warming in the pipeline now, which is not stopping- as we cross the threshold to 400ppm C02- I frankly do no see ice reforming unless C02 drops significantly- and even then it would take decades to restore the balance up north.

I don't have time to dive into this, but I'm wondering the same thing as with the Funder paper: are they taking an increasing amount of warmer waters into account? Or are they just looking at the winds? The winds are of course very important, until the ice gets too thin.

I didn't take time to read your post yet, Neven. But this seems an appropriate detail when 'they' are talking about 'a pause'. Not for Sermeq Kujalleq, yet. Melt is slowly reaching into the fjord's backbone.

Appears to be some circular reasoning in the article. In order to explain the greater than expected decline in arctic sea ice, they introduce the concept that half of the decline is due to natural variability. Looking ahead (and still assuming a large degree of natural variability) they then conclude that there will be more natural variability in the future. Like duh!

However, what if the current models are fundamentally in-adequate and natural variability is only about 15% of the decline? Then obviously, the future variability won't be all that great and we will witness summer time arctic sea ice volume approaching near 0 before the year 2020.

Also, they mention extent, but what about volume and area? Extent will probably end up as the most robust measure of sea ice since every winter will reset the area and then winds and currents spread it all about each summer.

This is my own ball park impression/calculation based on recent observations.

This isn't really new news, is it? Here, have a look at this snippet of an NYT piece:

"Dr. Brinkhuis and many other veteran Arctic researchers caution that there is something of a paradox in Arctic trends: while the long-term fate of the region may be mostly sealed, no one should presume that the recent sharp warming and seasonal ice retreats that have caught the world's attention will continue smoothly into the future.

"The same Arctic feedbacks that are amplifying human-induced climate changes are amplifying natural variability," explained Asgeir Sorteberg, a climate modeler at the Bjerknes Centre for Climate Research in Bergen, Norway.

"Indeed, experts say, there could easily be periods in the next few decades when the region cools and ice grows."

I wonder about this too, it seems that with the unprecedented rate of increase in temperatures and CO2 that pauses of a decade or more would be unlikely, or at the least counterintuitive. I think a stairstep rate of change is more likely, such as in the big drop between 2005-2007 and a plateau since may be how arctic sea ice changes. And it may be that we plateau near the 2007 level for some more years, so in that sense, the paper could be correct.

However I believe that the trend is clear, and that summer Arctic sea ice will be mostly gone by 2030 or so.

One feedback that could slow down arctic warming could be if the open Arctic Ocean releases much more moisture and snow depths deepen in the arctic land masses, which would resist spring melting better, and produce some local, temporary cooling. Or some other negative feedback might come into play that we don't know about.

But I stand by summer arctic sea ice being mostly gone (less than 1 million square km) by 2030, and by 2050 at the very latest.

Interesting research. IMHO, it makes perfect sense that the behaviour of polar ice is not going to follow a linear trend, even though as the authors emphasise the ultimate fate is almost sealed.
Things like the Pacific Decadal Oscillation (PDO) are likely to affect the trend and I can understand that we will see cycles spanning a decade or two, just like we see year to year variability.

Here in Australia, there is solid evidence that climate change is leading to a drier climate. However the summer of 2010-11 was the wettest in the last 50 years. It is almost certain that we will have cycles of wet years and dry years in future just as has been documented in this country since European settlement. There is no reason to believe that the same pattern wouldn't apply to the arctic.

I don't buy this model. Which emission scenario did they choose? What about volume? Extra heat from air and oceans is one thing, ice dynamics are another - inverting the spiral once it started requires strong events - I mean, when you start from one year, the next one can be higher of lower; but when you have years and years where the tendency goes downwards... Inverting this tendency is much more difficult - just try to stop a dam when it starts leaking for real...

For the record, I agree with you almost completely, though I think we'll reach zero-ice much sooner.

One problem with this type of thing is, of course, that denialists will ignore any large and overriding downward trend and instead latch onto any stabilization or increase, no matter how minor or short-lived. (They're already jumping on this study, distorting it to claim that Arctic Sea ice loss has stopped.) I guess it's just gonna make the job a little more difficult for us truth-tellers...

I published this first, on "Arctic tipping point may not be reached". These people are just cribbing from me!

Seriously, though, this does make a lot of sense. The Arctic sea ice is in decline, but it is likely to decline by fits and starts, not in a linear or particularly predictable manner. It has now entered a phase of chaotic turbulence.

As the Earth in general warms, new climate patterns may well arise, some permanent, some temporary, which interfere with the factors leading to the current Arctic amplification.

As the Arctic itself warms, the disappearance of the ice per se is likely to cause some negative feedbacks, which will temporarily reduce the melt.

The result, I predict, is that we will see an ice-free Arctic by "step changes".

But note that steps have risers as well as treads. In other words, in any year from now on, the level of ice cover could plummet to a new step down, abruptly and with little warning.

I should also add that, in my opinion, Maslowski is pretty close in predicting an ice-free Arctic by 2016 +/- 3 years, if a little conservative, given that his prediction dates from before the big crash of 2007. So I don't see where decades come into it. It will all melt away one summer, quite soon.

I am a bit more conservative on ice melt I guess, since the big decline in 2005-07 and the pause since hasn't been explained. I think pauses up to a decade may be possible, but it is hard for me to see us not seeing summer ice minima below 1 million square km by 2030. However it is possible that some sort of negative feedback may come into play that we don't know about. But by 2050, surely yes, summer arctic sea ice will be gone.

If I recall chaos theory properly adding energy to a chaotic system increases it's variability.

Weather is a chaotic system while climate, operating on a much larger scale is much less so.

Arctic sea ice extent is a product of both climate and weather. As the climate warms, weather's influence on ice extent will become more extreme, sometimes amplifying, sometimes negating the overriding climatic driver.

As the timescale is increased, the chaotic 'noise' of weather tends to cancel itself out.

Just as I'd suspect the dice if a player made 10 straight passes, I'd be leery of a model suggesting 10 years of enhanced extent against the present trend line.

It seems to me that the past few years could be one of those cases (as modeled) where ice extent doesn't decrease much, but it certainly has decreased in area and volume, due to "unfavorable" (in the sense that extent doesn't decline with the other measurments) weather patterns spreading the ice out.

Also, wintertime snow cover has increased recently, but it has also melted faster in the spring, as mentioned by the NSIDC a while back in their mid-July update (recall that albedo has a much bigger effect in the summer. Also, the snow cover anomaly for June, when insolation is highest, was over 4.5 million km2, over twice the sea ice anomaly).

"A climate model (CCSM4) is used to investigate the influence of anthropogenic forcing on late 20th century and early 21st century Arctic sea ice extent trends. On all timescales examined (2–50+ years), the most extreme negative observed late 20th century trends cannot be explained by modeled natural variability alone. Modeled late 20th century ice extent loss also cannot be explained by natural causes alone, but the six available CCSM4 ensemble members exhibit a large spread in their late 20th century ice extent loss. Comparing trends from the CCSM4 ensemble to observed trends suggests that internal variability explains approximately half of the observed 1979–2005 September Arctic sea ice extent loss. In a warming world, CCSM4 shows that multi-decadal negative trends increase in frequency and magnitude, and that trend variability on 2–10 year timescales increases. Furthermore, when internal variability counteracts anthropogenic forcing, positive trends on 2–20 year timescales occur until the middle of the 21st century. "

As with the recent Science paper by Funder et al. 2011. Kay et al provide evidence that climate models do not currently provide an accurate description of the behavior of the Arctic Sea Ice. That is, 'it is not all figured out'. (The corollary is that current projections are speculative.)

The clear implication of Kay et al. 2011, is that anthropogenic warming alone has not driven the recent reduction in Arctic Sea Ice; rather natural variability has also substantially contributed. Thus, where this natural variability is contributed by cycles that last for some period of years, the present sustained pattern of ice loss may not be continued. (In fact, Kay et al. contend that periods of sea ice expansion would occur.)

Perhaps the flurry of Arctic models will settle down by 2014. For now this empirical blog is as good a source on the Arctic as any. I encourage you again to look into heat sources including ocean currents and to think about how you might synthesize all that you know into a coherent explanation. Start thinking now; the ice won't last forever, and who better to write its story?

Ten years from now this year's climate, this year's models and this years Arctic will be history.

I noticed that arctic sea ice fell below 6 million square km on August 10, and to below 5.9 million square km on Aug 11.

But Aug 11 this year was 430,000 greater in ice extent than in Aug 11 2007.

True the state of the arctic sea ice is a lot poorer than in previous years, not as much area, lots of ratty weak 1st year ice.

Ice extent has been falling slightly faster than in 2007 in the past few days, and on August 11 2011 fell 2,818 square km faster than in Aug 2007.

The sea ice is in such a bad state that I expect we will tend to fall faster than 2007, but 430,000 is a lot to make up in 6 weeks. Have to average over 10,000 square km faster per day during the next 6 weeks and I don't think that will happen. This year.

I have my serious doubts about the ability of any model to predict any thing this specific in a system on the edge of chaos such as the rapidly changing Arctic. This model essentially comes to the same conclusion that all previous ones have-- the Arctic is headed toward a seasonally ice free condition from anthropogenic GH gases and related feedbacks, but this model is simple saying there could be longer pauses and bigger loops in that spiral down. This may or may not actually be the specific path the Arctic takes to an ice free condition, and I would argue the odds are pretty good that it will not be. There will be tipping points that are completely unpredictable by this or any model which will completely change the character of what is happening, and then that new input will be put into the next iteration of models and a whole new set of predictions will come out, which again will fail to predict the next tipping point, and so on. Essentially, the models are trying to predict the exact route on a journey that is being fueled by anthropogenic climate change, when in fact the best we can hope for is get the final destination correct-- we will have a seasonally ice free Arctic very soon from a geological perspective, and trying to predict exactly how we will get there is like trying to predict exactly where a snowflake will land when it starts to fall from a cloud. We know it will hit the ground somewhere, and each little air current that catches it and alters it's course is like a little tipping point, with a new climate model taking that into account in trying to better predict when and where that snowflake will finally come to rest.

"...since the big decline in 2005-07 and the pause since hasn't been explained."

The pause may be explained by a decline in solar insolation which started dropping steeply in 2002 and seems to have bottomed out at the moment.

If solar insolation were filtered out, the 'flatness' or 'pause' since 2002+ would not have occurred.

This would apply even more to 2010 and our current La Niña, which seems to be the warmest one so far. I don't know how much a temperature change that would have made (.1C?) but there would have been more melting.

Another issue to take into consideration is the 2007 La Niña. Had the El Niños that started in 2002 continued past 2007 then the drastic ice melt that year would have been even worse. The recovery would have been even less in subsequent years.

Put reduced solar insolation and a La Nina together and what do you get???

Those models cannot take every positive feedback loop into account. At this point, in the death spiral, good intuition based on a sufficient amount of knowledge is probably every bit as accurate as models.

I predict that models will be dead on when the last ice cube sized piece of ice is found bobbing up and down in the 35F+ ocean. :-)

Some skeptics would like to completely throw out models or discount everything they say. They are tools good at generalities, but poor at specifics. Recognize them for what they do best and what limitations are. Don't try to make a screwdriver into a wrench, and recognize that we haven't the tools yet for accurately seeing every turn or tipping point in a system on the edge of chaos, and possibly never will.

Current models work best on macro-sized areas and macro-sized timescales. They work best on century-to-millennial timescales and suffer badly on decadal timescales (though recent attempts now coming to market are going through calibration and validation).

They lack sufficient resolution to properly model the physical processes now at play in the Arctic. In this regard, Maslowski et al are developing a much finer-grained model that more accurately reproduces observed eddy processes in the Arctic, but that model is some ways out yet.

Simple physics and measurements we can make tells us the Arctic warms and will continue to warm. That the models cannot yet properly reproduce that does not reflect poorly on the models, for they are but tools being used outside of their design function.

Measure with a micrometer, mark with chalk, cut with an axe. We have taken the axe to the Northern Hemisphere's refrigeration system. Arguing about it will not changes the fact: the damage is already done.

All that is truly in question is how hot it will get and how fast the melt will occur.

There are about 20 recognized physic based GCM models. Some do a better job than others at modeling sea ice decline. Offhand, I'm not sure which is best and if this paper used one of the better ones or not.

Anyhow, the only observations that may be used to update models are physics based. That is direct and reproducible measurements. One that is very important for the Arctic is the albedo of snow and how it changes with temperature, sunlight and humidity.

The increase in NH winter snow fall is recognized by most models as it represents increased precipitation. This increase is evident in observations, especially for the months of November and December. However, for the rest of the year, snow fall extent is trending lower due to the warmer climate.

While this blog is about sea ice, the NH snow coverage probably has a greater impact on the climate of the arctic. How much falls, where it falls, how fast it melts and how much sunlight it reflects. However, the albedo of snow varies so much that very small changes in it's value could play a large role in future climate of the arctic.

Just wanted to let folks here know that I've got another science history article up--this one on the hunt for the 'solar constant.' It's Part One of a series; the forthcoming Part Two will deal with radiative transfer from there, examining some of the historical observational research on 'nocturnal radiation', 'earth radiation', 'sky radiation', 'effective radiation' and--well, you get the picture.

The pause may be explained by a decline in solar insolation which started dropping steeply in 2002 and seems to have bottomed out at the moment.

On your comment of steep fall of solar insolation, sorry guy, I'm not flying with that. I chart piles, in amongst the sun, and per SORCE, the 2011 TSI mean is 0.0091% lower than 2003 [lest me abacus is broken], and when adding ACRIM III to the SORCE chart, to get back to SC23 peak, it's still peanuts in watts/m^2 as a fraction, regardless of 24/7 daylight. See TSI SORCE-ACRIM-III chart

The only portion I'm concerned with on the sun is the ozone layer damage and it's consequential ease of EUV getting through more... UV/EUV is deep water penetrating.

BTW, I'm a big fan of Wayne Davidson's Extreme High Horizon Refraction blog. Something's in the Air [Thunderclap Newman]

P.S. ACRIM has not published later daily data beyond day 122 that I can find, hence the gap at the far end.

In "The future of ice sheets and sea ice: Between reversible retreat and unstoppable loss" PNAS 20590–20595 December 8, 2009 vol. 106 no. 49, Notz wrote; "A second conclusion that can be drawn from considering the shift in the ice-thickness distribution is the fact that with a thinner sea-ice cover, the size of the area that becomes ice-free during summer depends much more on the actual weather during a particular summer than is the case for thicker ice. Therefore, with the ongoing thinning of the ice cover (23, 25), we are likely to experience both large negative and large positive year-to-year changes in Arctic summer sea-ice extent. This variability directly implies a much-reduced predictability of sea-ice extent a season ahead than does thicker ice. The increased variability will continue until most of the ice cover is thinner than the typical summer melting rate, at which point most of the ice will disappear during summer, with only small year-to-year changes. The decreased predictability that goes along with such an increase in variability was also found in a recent more complex modeling study (27)."

Jeff Masters over at Weather Underground believes 2011 will give 2007 a run for the money over the next couple of weeks:

"A strong high pressure system with a central pressure of 1035 mb has developed over the Arctic north of Alaska, and will bring clear skies and warm southerly winds to northeast Siberia and the Arctic during the coming week, accelerating Arctic sea ice loss. Widespread areas of northeastern Siberia are expected to see air temperatures 4 - 12.C (7 - 22.F) above average during the coming week, and the clockwise flow of air around the high pressure system centered north of Alaska will pump this warm air into the Arctic. Arctic sea ice extent, currently slightly higher than the record low values set in 2007, should fall to to its lowest extent for the date by the third week of August as the clear skies and warm southerly winds melt ice and push it away from the coast of Siberia."

Not to sound like an anti-science Bible-beating fundamentalist, but the only "model" I need to tell me what's up is the "PIOMAS monthly average arctic ice volume with exponential trend" graph, which shows that September of 2010 had less than ONE THIRD the ice that September of 1980 did.

Area and extent have shown modest "recovery" since 2007, but the volume is still plunging.

All the discussion reminds me of the lecture in ecology class about extinction and the kinds of population cycles that lead to extinction. Many animals have wildly fluctuating populations with boom-crash cycles, but some of the animals that are most vulnerable are animals that have wild population swings and very low starting populations. If a species regularly goes from 10 million animals to 100 million animals and then crashes back to 10 million, it's a much less vulnerable species than a species that goes from 100 animals to 1000 animals and then crashes back to 100 animals.

Similarly, a wild fluctuation of 5000 km3 of ice didn't look so alarming when the starting volume was 17,000 in September of 1980, but now that the total ice volume coming out of September of 2010 is only 5000 km3 total, such a fluctuation could be the end of the death watch and the start of the wailing and rending of garments.

Just to note that models and observations have had plenty of conflicts over the years, and that often enough these have been resolved in favor of the models. I don't expect that to happen in this case, though.

Kevin, the loss of the ice is different than the loss of a species, unless the loss of the ice leads to the loss of species or the destruction of functional ecosystems. I was throwing it out there as an analogy though. :D

Though I liked the remarks FI by Daniel and Andrew, that pretty much wrap up the general usefulness of climate models, I started doing some homework myself on the topic.
First, Gavin Schmidt has an interesting post on RealClimate about the effort to integrate most used models on behalf of the coming IPCC report five, within two years from now.
I’m sure the NCAR model, CCSM4, will be an important one in that effort. You can make your own evaluation, through reading this, how ‘serious’ the NSF publication should be taken. Remind, there’s always an element of politics and a dash for attention (I know, I like that too...).
Second, the NSF article states ‘...though the model has certain biases...’. Through Wiki I learned that there are actually a lot in most models.
My hunch is that the behaviour of evaporation/convection/ clouds is the main difficulty. When I stumbled upon that, having influence on the state of the upper troposphere/stratospheric cooling, Wayne Davidson’s name got in my mind again. Whatever I can make of his work now, I feel there’s this ‘interdependency’ of the system he’s after. Would Davidson work on/use any models?
Third, the NCAR team has been modelling on ice cover and ‘tipping points’ for a lot of time now. I found an article dating to January 2007. Six months before the dramatic extent decrease that year, they didn’t see it coming... Later, in an article early 2010, Holland still answered that there was no evidence for a ‘tipping point’.
My prelim conclusion: scientists are balancing between reticence and speaking out. That’s a difficult job. Any info published can be taken out for whatever interpretation.
While reading a head like ‘A.I. melt could pause...’ make your mark on the verb: ‘can’. Easy semantics: big difference with ‘will’!

Short remark, can't resist to hold that back.... While reading, I saw that on extent, in 2011 we are some twenty years ahead of the average model outcome as published (a couple of years ago, think 2008).

I've been posting comment on a denialist dominated discussion forum for a while, and more recently made a few posts here.

Just a comment.

I'm somewhat suprised at how little interest the forum members here seem to have in the scientific literature. I see quite the same reaction to the literature from my posts on the denialist dominated forum. It appears that nobody wants to actually read what scientists write and try to understand it.

Tzupancic1, I don't speak for the others here, but just for me. I mostly content myself with reading this forum, chipping in when I can.

The Arctic is not my area of expertise, but reading as much of the literature as I can and corresponding with glaciologists and climate scientists, it's my opinion that the literature lags developments in the Arctic.

If the others here share that opinion, perhaps it's no surprise that they feel little need to discuss the literature itself, but give priority to discussing developments in the Arctic in real-time, as they happen.

If you wish to discuss the literature itself, either write up some synthesizing piece on the literature or on a singular piece of the literature and submit it to Neven as a guest post or to Skeptical Science (where I write occasionally and moderate as well).

Also at SkS is extensive ongoing discussion of the literature as a whole, not just restricted to that pertaining to the Arctic.

Tzupancic - I don't think I can agree with you. Neven has highlighted numerous papers here. And the comments are littered with references to various papers.

Now, has every poster read every paper concerning the arctic, arctic sea ice, paleo-climatology, etc - of course not. Most are familiar at least with the concepts discussed. Only a few seem to have a closed mind on the subject.

Of course the beauty (and the inanity) of the internet and blogs is we all get to voice our opinion - regardless of how ignorant we might be. Hopefully I'm not guilty too often :) In the short time I've been visiting here I've seen people change their beliefs based on the most recent published research; Maslanik and Tiesche especially.

I read The future of ice sheets and sea ice: Between reversible retreat and unstoppable loss and it confirmed many ideas I've read elsewhere. I bookmarked it for the portions on the Small Ice-Cap Stability problem.

Tz - I occasionally see a post that I dislike the poster's tone (perhaps what you mean by arrogance) or the dismissal of published work without a sound rationale backed by other published works. These are usually by new visitors and I ignore them. The people who have posted here for any length of time are almost without fail able to discern fact from opinion - and admit their own incomplete knowledge.

The literature says that the arctic will be seasonably ice-free in several decades. Now, if the belief here is that this is understated - then you're right. Most here believe this is incorrect - the timeframe will be much shorter.

Is that arrogance? I don't think so. The GCMs have completely missed the large decreases in volume and extent. Those who work with the GCMs know they have limitations; some are better at sea ice than others - none do it well (as the MIT study points out). The errors have been without fail on the conservative side.

So, given that the models have known problems it's hardly arrogance to disagree with them on the subject of sea ice. From that point it's simply a matter of whether one has a belief that is supported by science or simply wishful thinking.

"The simulations also indicated that Arctic sea ice is equally likely to expand or contract over short time periods under the climate conditions of the late 20th and early 21st century".

I don't see how this can be mathematically true. Even if AGW is only responsible for half of the sea ice loss since 1980, that is something like 3 1/2% per decade. Whatever the standard deviation of the annual ice change is, the expected value is still a loss, with a higher probability of loss than gain in any given year. The probability of net ice loss increases for longer periods of time, eventually approaching 100% (the house always wins eventually).

TomZ - I really think we're in uncharted territory. Even an educated guess is still a guess.

Given the MIT study are Tiesche's results now in question? Would a GCM that correctly handles the coupling between ice thickness/concentration and drift yield the same results?

One thing that must be considered in respect to Funder's results is that past Arctic warming was not homogeneous. While Greenland's shores saw open water other parts of the arctic saw increased ice. We do not see anything comparable today. The entire arctic is warming.

The single question I'd like to have answered is: Could decreasing sea ice extent lead to a trans-polar surface current?

I am not sure which paper you are referring to but I haven't read it. It just doesn't seem possible that the probability of an increase is "equal" to the probability of a decrease in the short term when the slope of the expected amount of ice is always negative, regardless of the variability. Perhaps the function is of such complexity that it is "expected" that there will be reversals but I would need to be convinced of that.

Mike (yahoo assigned me this stupid moniker and I don't know how to change it).

Yes. But the line is going from current value to zero in a few decades, so the slope of the expected ice extent (or area or volume) is always negative. This means that it is more likely that extent will decrease than increase in any given short-term time frame. Even if variability is extreme.

As we move from a stable system, through a chaotic phase towards another stable state predictions become more difficult

The present lack of successful models indicates that we are well into chaotic regions

An overall downward trend evident in all metrics may indicate a rapid transition, the details may be impossible to forecast on a micro scale, literature and models 3 or 4 years old may have little relevancy

Mike - it doesn't necessarily work that way. You could see large variations in both directions - as long as the decreasing variations are larger in total than the increasing variations you'll still arrive at zero.

One of the most intriguing papers to come out in awhile, that you'll find referred to time and again around here is: Tietsche et al, 2011, "Recovery mechanisms of Arctic summer sea ice."

I read the summary of the paper and I think I get the gist of it. Perhaps the pattern of decreases and increases will produce few large negative changes and frequent small positive ones. But if extent goes to zero in 50-60 years I doubt if there will be but a few cherry-picked decade-long periods where extent has increased (consider the anomaly of the 1998 to 2008 global air temperature drop versus all the positive decadal changes since the late 1970's). The paper said the chances of a decrease or increase in sea ice over a random decade are "equal". I don't buy it.

I read Nevens Sea Ice Blog as a source of information on a subject that has interested me since I first got online (c. 10 yrs). There is also a mine of information in http://www.science20.com/profile/patrick_lockerby for the history and current state of things.

Fundamental observers have been saying that the Arctic in particular has been changing to warmer conditions over that time.

The scientific literature has all shades of opinion but models seem largely to lag the changes on the ground. (And when "warmers" overstate their case it will be jumped on by the "deniers", so caution/inertia has the advantage!).

In fact I feel the tone of the basic article above seems unduly speculative, and to be pandering to those who want to continue not to think about the future. I fear that humans often try to cure the symptoms, not the causes, and in this case maybe we can make the symptoms a figment of our imagination?

Mike (yahoo assigned me this stupid moniker and I don't know how to change it).

Haha, I wish Yahoo assigned a name like that to me.

I'm somewhat suprised at how little interest the forum members here seem to have in the scientific literature. I see quite the same reaction to the literature from my posts on the denialist dominated forum. It appears that nobody wants to actually read what scientists write and try to understand it.

Why is that?

Tom Z, speaking for myself: I don't have the time, competence or mental energy to read scientific papers (I do collect them in a special folder though). And certainly not right now. But you won't hear me say I've got it all figured out either.

This issue then brings us to various publications that provide reasons to expect periods of sea ice extent increase or stasis during a long term decline. (eg. Funder et al. Science; 2011, and then Kay et al. GRL 2011' for eg.

Turning it around, if the models can't explain the present, there must be some element of the system that is not being considered by the models. Kay et al. suggest this element is some natural variability. But what is it?

One more; considering the implications, consider that Kay et al. are correct, and there is a period where sea ice extent holds steady or even increases for a while? How will the denialosphere respond? Imagine a year or two with a return to 2006 minimum levels? If this is something that could occur, would it not be wise to be prepared to explain what is happening?

Well, should there be a decade-long pause in the SIE decline, the denialerati would certainly be predicting an Ice Age. Hell, some were predicting an Ice Age by the end of January last, just because we had a negative monthly anomaly (UAH baseline, of course.) Not too much to be done about it, I'm afraid; we would be able to point to studies like Kay et al., but with only limited effect.

That's the lesson of the last couple of years, anyway. By 2008, SIE was said to be 'recovering,' and it took the minimum of 2010 to make them consistently change the subject to something else--say, Dr. Monnett (to take the most recent meme.)

While there has been a dramatic reduction in Arctic Sea Ice in the past few years, there are reasons to see how this pattern could change. Maybe not, but it is worth while to understand how the system is behaving in greater detail.

TomZ - You may appreciate Chris R's blog. Chris is exploring the mechanisms of arctic sea ice loss and reviewing much of the literature. His blog is titled Dosbat and you can find it at http://dosbat.blogspot.com/

I've posted enough here so that everyone should by now know I know next to nothing about Arctic ice. But rather than letting that stop me from asking what is likely a stupid question -

What is it that could turn this great melt-out around?

We have no data that suggests the Sun will dim, nor Earth's orbit suddenly shift.

I've heard no great theory that holds once global temperatures rise to a certain point some strange change will cause warm winds to no longer blow into the Arctic.

Does someone predict the cessation of the North Atlantic Current happening soon?

I'm just not grasping the meat of the Kay paper. All I get from it is there is a certain amount of (apparent) randomness in physical systems and if all the ducks lined up just right then ice could return for a while. But I find myself wanting more than a simple statistical possible outcome. I'd like a physical cause.

I can see a pause if multiple high latitude volcanoes popped in a timely fashion in order to create a few years of Arctic dimming. But short of that I'm perplexed.

If one looks at Maslowski's "death spiral" graph and projects the lines forward it's hard not to assume an ice free September in about five years. Let lightening kick off a few more peat fires, pile some albedo-killing carbon particulate on the remaining ice and that time frame could get shortened.

To me, this is a somewhat simple system. Over winter the Sun does not shine, accumulated heat leaks off, and water freezes. Over summer Sun and soot work together to melt ice and since the planet is overall warming, more heat coming from outside is causing a progressive loss of accumulated ice. Throw in some heat transportation from outside the area and an increase in imported heat due to ocean warming.

I just don't see the planet cooling, the oceans cooling. We aren't even beginning to reverse the heating, we're continuing to pour on the coal.

So, help me out please. What are the possible/reasonably probable variables which could come into play and ice things back up?

if the models can't explain the present, there must be some element of the system that is not being considered by the models. Kay et al. suggest this element is some natural variability. But what is it?

Bob, we pretty much can take as a given that ice will reform in sizeable amounts every winter.

So, if we have millions of km^2 of ice to start every spring, then a cool/cloudy summer means much of it will survive summer. Put a couple back to back cool summers together (easily within the realm of weather variability) and thick multi-year ice can form.

The other more speculative answer is changing weather patterns due to less ice acting as a negative feedback. The Beaufort Gyre has traditionally acted in this manner - but even the gyre can only do so much. I don't think anyone is saying the arctic is going to ice back up - not to pre-2000 level; probably not even to pre-2007 levels. But we shouldn't expect a catastrophic loss either.

In the end, you're pretty much right to wonder ... doesn't seem there are any realistic lifelines left for the arctic. We're left with an office pool guessing how many years until it's ice free: 5 yrs, 10 yrs, 30 yrs --- not even the blink of an eye geologically.

I can also speculate that some immense system might form below the Arctic which would block the flow of warmer air northward. Like the enormous high that parked itself over the Southern Midwest this year.

As for the models not being able to predict, it may not be that they are missing elements. It might be that the modelers have been overly cautious in dialing in sufficiently strong amounts.

It feels to me that climate scientists have received such an intense attack from outside forces that they might be erring way on the conservative side. I have a feeling that behind closed doors they might be telling each other that there's a lot more poop hitting the fan than they can admit to the outside world.

I look at how Hansen and a few others have been treated and wonder if other scientists are holding back for career reasons.

I worry that we have beaten up so badly on our guides that they are feeling that they can't be honest with us about how treacherous the path ahead of us actually is.

It's late and this has been mostly hashed to death, but here's a bit that needs sayin':

No one has (to date) done a better job of modeling the actual degradation and loss of Arctic Sea Ice than Maslowski. His model output is thus far withstanding the test of time. Until his new, refined model with improved eddy prediction/simulation is ready, his earlier prediction of 2016 +- 3 years still is the gold standard to beat.

If other models fail to measure up, than their operators need to consult with Maslowski. Speculating on what those other models are missing is pointless and a waste of time (but see the recent MIT study for a point in one direction).

Real time events have left all other models behind, with only Maslowski still in the running.

Tom Z, are you familiar with the tropicalista Tom Zé? http://en.wikipedia.org/wiki/Tom_Zé
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I'm not sure this great ice-empiricist blog would be much improved by digging into why various models under-predict the melt. Instead that might bog the blog down. For my part I seem to read a climate paper or a good chunk of one if it's long most days, although I don't start with that intention.

A climate model (CCSM4) is used to
investigate the influence of anthropogenic forcing on late 20th century and early 21st century Arctic sea ice extent trends. On all timescales examined (2-50+ years), the most extreme negative observed late 20th century trends cannot be explained by modeled natural variability alone. Modeled late 20th century ice extent loss also cannot be explained by natural causes alone, but the six available CCSM4 ensemble members exhibit a large spread in their late 20th century ice extent loss. Comparing trends from the CCSM4 ensemble to observed trends suggests that internal variability explains approximately half of the observed 1979-2005 September Arctic sea ice extent loss. In a warming world, CCSM4 shows that multi-decadal negative trends increase in frequency and magnitude, and that trend variability on 2-10 year timescales increases. Furthermore, when internal variability counteracts anthropogenic forcing, positive trends on 2-20 year timescales occur until the middle of the 21st century.

To me, it seems that Kay et al 2011 reports that variability in sea ice is increasing in a warming world, and this can lead to 2-20 year stretches of counter-intuitive sea ice trends. Since we have been way (sime two sigma's) below the GCM ice trend expected for the first decade of the 21st century, Kay et al can only attribute half of ice melt to antropogenic forces. IOW, ice melted much faster than the models can explain.
Kay et al 2011 thus suggests that there could easily be a decade of ice extent increase, so that the trend line catches up with the model trend average.

Meanwhile, they re-emphasize that somewhere (halfway) this century we will be faced with ice 'free' summers in the Arctic.

Another explanation would be that in fact GHG forcing is the primary driver of Arctic climate change, and that the excessive ice losses over the past decades are simply the result of IPCC models underestimating albedo effects and ice insulation effects, and overestimate cloud adjustments in a warming Arctic. If that's the case, we may see this high variability that Kay et al suggests last only a decade, after which virtually ice free summers would be the norm.

Have not seen anyone disproving that scenario.

Either way, I think that the blogosphere emphasis on the "melt could pause" and "expect more ice with global warming" are at a minimum deceptive and 'cherry'-picked only the last sentence from the abstract of this very interesting paper, the first one (AFAIK) that dares to put a level of attribution to human GHG emissions on the ice losses in the Arctic.

As mentioned earlier, there is active research on snow (ice) albedo in an effort to develop better models for use in GCM climate models. My own suspicion, is that this is an underlying cause for most models bias in the Arctic.

Also, Figure 1.A is interesting:

Rather odd how the trend was originaly strong for December, but has since diminished for that month while the Sept/August trend is now dominate.

I'm with DB on this one. Maslowski is the only one anywhere near the reality we see.

As it happens, my own view is that there's far too much emphasis on transitory and unreliable factors - insolation, soot, clouds, winds, weather. The relentless one seems to be overlooked.

The never-ending, 24/365 contact beneath the ice with the always warming ocean. Currents may vary with tides and winds. But the water is always there, and it's always warmer than it was 30 years ago.

People who describe the ice as 'recovering' for any period at all from now on are a bit like iffy estate agents. Maybe hopeful buyers won't see the termites in the floors or the rotting rafters. Coupla coats of bright'n'shiny paint and she'll be right.

"I'm with DB on this one. Maslowski is the only one anywhere near the reality we see".

All the other models seem too conservative for the rate of loss of sea-ice in the Arctic. It could easily be said that weather was the 2007 problem, but things had started long before then.

In the Southern Hemisphere whole ice shelves have collapsed (and dispersed like sea-ice!), together with increased flow from their attendant glaciers, which might account for rising levels of sea-ice there? The collapses seem to have followed an unusual melt, which would indicate an underlying warming trend there too.

In the north huge floes at the edge of the ice can shatter and seem to disappear in a few days, while misty swirls of ice around southern Greenland and the Foxe basin seem to drift on all summer! It is also interesting to see how much snowier the east coast of Greenland appears than the west.

I cannot yet see any driving force that will reverse increasing melt, which in my opinion it usually estimated conservatively in order not to be too alarmist

The amount of cooling that will have to take place to achieve any comeback would be dramatic on the global scale.

Like beyond absurd.

How long will this go on? Every Year it's it will start rebounding next year.

Yeah we may see a 1996 here and there but that will go like it went because it will be a mirage of thin ice being destroyed by the warming planet.

This natural cycle is at it's bottom point. The ice from all the historical data started to drop in the early 70s. But even just Sat Era we are entering year 33 of this come November and we are at the bottom still.

the problem with any sort of so called natural cycle is that it will take 10 times as much cooling compared to the warming now for the ice to go back to the 70s levels. We are talking about gaining 70+ percent of the ice volume back. Thick old ice that possibly took decades or centuries to accumulate into large deposits some hundreds of meters deep that are gone.

If we had bad winds this summer we would be talking a 3-3.5km2 min.

this summer was pretty damn good in terms of winds. To bad the air and oceans are warm

As has been pointed out, the long-term trend of Arctic Sea Ice volume loss will continue as long as the overall global warming trend continues. As we are now on the 316th consecutive month above the long term 20th Century average for global temps, there will be no "recovery".

(The last month where global temps were at or below the 20th Century average was February 1985...)

Tom,
There must be more heat accumulating in the Arctic than there was in the past. The literature has not pinned all the causes down yet so I can only look at the symptoms and speculate why.

The obvious culprits are:-
!) CO2 - it was forecast that it could warm climate a long time ago.
2) Reduced albedo from reduced snow/ice cover.
3) Transport of heat by air and water from more southerly latitudes.
4) Cloud cover - can be +/- depending on type, time of day/year, (and the way the wind blows!).

I was among those who expected a more spectacular decrease in arctic ice this year, but the complacency of the "business-as-usual" and "more opportunities" brigades concerns me.

Sea ice could recover if something changes, but i put that in the"pigs-might-fly" wishful thinking category at the moment. Better minds than mine are assessing the situation, but I wonder how much influence they can have when the 'drill, baby, drill" team are working?